[Elecraft] KPA500 question

Wed Jun 15 18:39:38 EDT 2011

 > Anodes towards K3/KPA500 signal junction. Just one diode needed per
 > BCD signal.

No, that will not work since anode to K3/KPA500 will not allow the K3
to pull the RCS-12 inputs low.  Since I don't have a schematic for the
RCS-12 (none published as far as I can fine), my assumption is that
the RC-12 has pull-ups on its BCD input.

I suppose Dave could measure the voltage on pins 1,2,8 & 9 of the
RCS-12 "Radio Input" jack.  That would give some hint as to the
circuit design.  (I don't know why I'm trying to debug MFJ stuff -
just get a real band decoder <G>).

73,

    ... Joe, W4TV

On 6/15/2011 6:18 PM, Jack Brindle wrote:
> Nope. That won't work. The BCD outputs are open drain/collector, so
> connecting them in this way will actually do nothing.
> Anodes towards K3/KPA500 signal junction. Just one diode needed per BCD
> signal.
>
> Jack Brindle, W6FB
>
> On Jun 15, 2011, at 3:06 PM, Joe Subich, W4TV wrote:
>
>>
>>> What kind of isolation diodes would you suggest?
>>
>> Any switching diode (1N4148, etc.) would be fine.
>>
>>> Any how should they be connected?
>>
>> As any set to isolation diodes ... two diodes per data line (A,B,C,D)
>> cathodes to the K3, anodes to the RCS-12 and KPA-500.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 6/15/2011 12:11 AM, Dave Perry wrote:
>>> Joe,
>>>
>>> Yes, I am using the four pins corresponding to Band 0 through Band 3
>>> plus the pin for ground. The RCS-12 works fine connected directly to the
>>> ACC port on the K3. It also works fine when the KPA500 is connected via
>>> the Y cable. It is just that the KPA500 is not switching bands when
>>> connected with the RCS-12. So your suspicion may be correct. What kind
>>> of isolation diodes would you suggest? Any how should they be connected?
>>>
>>> Thank you.
>>>
>>> Dave, N4QS
>>>
>>> ----- Original Message ----- From: "Joe Subich, W4TV" <lists at subich.com>
>>> To: <elecraft at mailman.qth.net>
>>> Sent: Tuesday, June 14, 2011 10:43 PM
>>> Subject: Re: [Elecraft] KPA500 question
>>>
>>>
>>>>
>>>> You might try isolation diodes between the antenna switch and/or
>>>> KPA and the K3. If the KPA is not band switching with the RCS-12
>>>> connected, I would suspect the RCS-12 is loading the band data
>>>> lines.
>>>>
>>>> How are you connecting the RCS-12? Are you using the "Yaesu BCD"
>>>> connections?
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>>
>>>> On 6/14/2011 11:24 PM, Dave Perry wrote:
>>>>> Gary,
>>>>>
>>>>> Good suggestion. I removed the cable going to the antenna switch and
>>>>> now the K3 and KPA500 appear to talk to one another when changing
>>>>> bands. Pushing a band button on the amp changes the amp and the K3 to
>>>>> the new band. I still cannot get the two power levels to work. I also
>>>>> need to figure out how to get the band switch working with the Y
>>>>> cable.
>>>>>
>>>>> Dave, N4QS
>>>>> ----- Original Message -----
>>>>> From: Gary Gregory
>>>>> To: Dave Perry
>>>>> Sent: Tuesday, June 14, 2011 10:12 PM
>>>>> Subject: Re: [Elecraft] KPA500 question
>>>>>
>>>>>
>>>>> What bothers me is the amp was not switching bands you said?...If the
>>>>> OPER switch is set then the aux cable should allow you to switch
>>>>> bands either way and the amp should indeed switch bands and indicate
>>>>> that on the LCD.
>>>>>
>>>>>
>>>>> Unfortunately, my FT unit has the original I/O board so I can't
>>>>> verify this for you...sorry
>>>>>
>>>>>
>>>>> remove the antenna switch and try see if that makes any difference.
>>>>>
>>>>>
>>>>> Gary
>>>>>
>>>>>
>>>>> On 15 June 2011 13:02, Dave Perry<n4qs at comcast.net> wrote:
>>>>>
>>>>> Gary,
>>>>>
>>>>> No, I did not remove any pins on the cable. This is the one supplied
>>>>> by Elecraft and I figured that it would be good to go. I just checked
>>>>> the cable and five pins have been removed. I just removed the Aux
>>>>> Cable from the back of the KPA500 and now the band buttons work on
>>>>> the amp. So it does appear that the Aux Cable is the culprit.
>>>>>
>>>>> Dave
>>>>> ----- Original Message -----
>>>>> From: Gary Gregory
>>>>> To: Dave Perry
>>>>> Sent: Tuesday, June 14, 2011 9:49 PM
>>>>> Subject: Re: [Elecraft] KPA500 question
>>>>>
>>>>>
>>>>> Do you have PIN 10 removed on the KPA-500 end of the Y cable?
>>>>>
>>>>>
>>>>> Gary
>>>>>
>>>>>
>>>>> On 15 June 2011 12:33, Dave Perry<n4qs at comcast.net> wrote:
>>>>>
>>>>> My KPA500 sn 70 arrived tonight (factory assembled). It took just a
>>>>> few minutes to hook up and get it on the air. I am using the Y cable
>>>>> on the ACC port to split off two cables from the K3 ACC port -- one
>>>>> goes to a new RCS-12 Automatic Antenna Switch and the other goes to
>>>>> the KPA500.
>>>>>
>>>>> I have AUX BUS on the KPA500 menu turned on and Band Change set to
>>>>> normal. If I press a band button on the amp, the K3 changes bands and
>>>>> so does the new antenna switch -- pretty neat. But the band display
>>>>> on the KPA does not change. I have to hit the key and transmit to get
>>>>> the band to change on the KPA500. This does not seem correct. It
>>>>> would seem that pressing any on the band buttons on the amp should
>>>>> change the band on the amp and the frequency display as well.
>>>>>
>>>>> Likewise if I change bands on the K3 or via my logging software, the
>>>>> K3 and antenna switch change bands, but the KPA500 does not. I have
>>>>> to tap the paddle and transmit to get the KPA500 to change to the
>>>>> correct band. I am wondering if there is a problem with the Aux
>>>>> Cable. Any other suggestions?
>>>>>
>>>>> I am up to date on firmware for both the K3 and KPA500.
>>>>>
>>>>> The amp runs very quiet and is silky smooth in full QSK mode. I just
>>>>> need to get the band changing issue resolved. Any help would be
>>>>> appreciated.
>>>>>
>>>>> Thank you.
>>>>>
>>>>> Dave, N4QS
>>>>> ______________________________________________________________
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>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> VK4FD - Motorhome Mobile
>>>>> Elecraft Equipment
>>>>> K3 #679, KPA-500 #018
>>>>> Living the dream!!!
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> VK4FD - Motorhome Mobile
>>>>> Elecraft Equipment
>>>>> K3 #679, KPA-500 #018
>>>>> Living the dream!!!
>>>>>
>>>>> ______________________________________________________________
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>>>
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